In a construction field and the like, double glazing has been heretofore used for the purpose of heat insulation; dew condensation prevention, sound insulation and the like. As such double glazing, there has been known double glazing having glass plates, a spacer placed between the peripheries of the glass plates and an airtightly sealed air space defined by the spacer between the glass plates, the spacer being formed of rubber, resin or the like having a drying agent mixed therein, the airtightly sealed air space being shut out from ambient air (see Japanese patent application Kokai publication Nos. 10 (1998)-110072 and 2001-354949, for example).
The double glazing described above is manufactured, for example, by extruding a spacer forming material from an extruder along the peripheries of two glass plates held with a predetermined space therebetween, before the material is cooled (see Japanese patent application Kokai publication No. 8 (1996)-67537, for example).
There is also a method of manufacturing double glazing by extruding a spacer forming material in a strip shape along the periphery of one glass plate thereon using a ram pressure type device, before press-attaching the other glass plate thereon.
However, in the former method, since the spacer forming material is extruded directly from the extruder, the cross-sectional shape of the extruded spacer forming material becomes unstable when the extrusion is started and finished. Thus, there is a problem that an airtight effect for the air space provided by the formed spacer becomes unstable.
In the latter method, since the ram pressure type device is used to apply the spacer forming material, a hot-melt type material is required to be used as the spacer forming material. Thus, there is a problem that the type of the spacer forming material to be used is limited.